Method for high-frequency telephony with or without a. line



April 21, 1925. 1,535,037

L. PUNGS METHOD FOR HIGH FREQUENCY TELEPHONY WITH OR WITHOUT A LINEFiled Aug. 23, 1921 FIG.4.

(,mpling Coib M60413 PIIOIL F|G.3. T INVENTOR: LEO Pu-6 JJO TelephonyVith or \Vithout a Line (for' Patented Apr. 21, 1925.

UNITED STATES PATENT OFFICE.

LEO PUNGS, 0F BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR TO, C.' LORENZAKTIENGESELLSGHAFT, OF LORENZWEG, BERLIN-TEMPELHOF, GERMANY.

I METHOD FOR HIGH-FREQUENCY TELEPHONY WITH 'O'R WITIEOUT A LINE;

Application filed August 23, 1921. Serial No. 494,570.

To all QIILOHZ it may concern:

Be it known that I, Lno PUNos, residing at Berlin-Char]ottenburg,Germany, have invented certain new and'useful Improvements in Methodsfor High-Frequency which I have filed application in Germany on June 17,1920), of which 'the following is ,a specification.

It has become known to use, for influenc-- ing high frequency currentsfor telephony with 'or without line, coils with iron cores whosemagnetizing is varied from a microphone under interposition ofstrengthening tubes. i

lVhen the anode current of the tube is used directly for themagnetization a determined anode current is produced with the microphonenot used for talking, the so-called closed circuit current of the tubeand consequentlyalso a determined magnetization of the iron and of thecoil. There exists for the coils a determined favorable closed circuitmagnetization for the value of which the magnetization produced by thetalking currents must fluctuate.

According to the invention this closed circuit magnetization is adjustedto the most favorable value independently from the zero current of thetube by means of special auxiliary means. This can be effected invarious manners. Either, besides the real winding, a second winding isused for the strengthened microphone currents, said second winding beingfed with an auxiliary current. This auxiliary current is adjusted sothat the resulting magnetization from auxiliary current and closedcircuit current of the tube gives the desired most favorable value ofthe closed circuit magnetization. Or the high frequency winding can beutilized directly for the introduction of an auxiliary magnetizingcurrent. In this case the switching-on of protecting choking coils andthe like is required.

A still simpler means consists in adjust;

ing the anode current of the tube when the microphone is not used fortalking, to a .value which produces the correct closed circuitmagnetization in the iron. This is obtained by laying on the grid of thelast tube a sufficient-1v great positive voltage.

which produces the desired anode current as closed circuit current. Thisvoltage can ,be made adjustable, The winding upon the iron core must bedimensioned accordingly. A separate winding and separate source ofcontlnuous current is under these circumstances not required for theauxiliary magnetlzing current. I

In the accompanying drawings in which like 1 reference charactersdesignate like parts throughout,

Figure 1 shows that form of the invention in which an auxiliarymagnetizing winding is employed.

Figure 2 showsf'that form of the invention in which'themagnetizinghurrent for the core is derived from the anode current of thetube,

Figure 3 is a chart showing the relative values of grid voltage andcurrent.

Fig. 1 shows a form of execution of the method by means of a separateauxiliary magnetizing winding. a is the coupling coil of the highfrequency generator (e. g. machine, arc light, tubular sender); Thiscoil (1 is fed from the high frequency generator arranged in the circuitin the usual manner and transmits the high frequency oscillations byinductive coupling tothe antenna, as coil a has inductive coupled withcoil 6. b is the, tuning coil in the antenna circuit, f the coil withiron core for the influencing of the telephony, 0 the high frequencywinding, of theniagnetizing current proper Which is fed from thestrengthening tube 9. The grid of this tube" is influenced in the wellknown manner across the transformer h from the microphone 70 which isinserted in the circuit of the battery 'When the microphone is not usedfor talking the current of the tube would adjust itself upon any valuewhich corresponds with a grid potential determined by the voltage dropat the filament of the tube. This closed circuit current is given by theconstruction'of the tube, the size of the same and so on. The givenmagnetization will. not correspond with the most favorable value of theaverage magnetization but be much lower. In order to be able to adjustthis most favorable value, a further winding 6 is provided, according tothis invention, upon the iron core, saidwinding being fed across aresistance from a source of continuous current. Through adjustment ofthe current in this winding the most'favorab le value of the closedcircuit magnetization n the coil can be determined. The winding ispreferably arranged so that it is not effective by the high frequencycurrent.

In Fig. 2 another form of executlon of the method isshown in whichseparate auxiliary winding and source of current are avoided. As alreadymentioned, the anode current is utilized for adjusting to the correctmagnetizing value this being effected bylthe insertion of a voltage intothe grid circuit, e. g. by means of a battery. This battery canevidently be small as it has almost no consumption of current. The1nserted voltage is preferably made variable which can be effected bymeans of a cellswitch or of a'potentiometer or the like.

Fig. 3 represents the known dependency between the grid voltage and theanode current in cathode tubes. When no grid voltage existed the anodecurrent would adjust itself to the value J 0 or to a value which I isonly little different from this value. By the addition of a positivegrid voltage E9 the anode current Ja is obtained. E9 must be selected inthis case so that Ja produces the most favorable magnetization.

The examples cited do not exhaust the possibilities of executing themethod as for example the two methods can be combined, that is to sayspecial winding for the aux iliary magnetization and adjustment of theanode current by a positive grid potential. The independency from thisnormal closed circuit current of the tube is important.

For greater efiiciencies several tubes can be used in parallelconnection, the grids of the tubes being then controlled by a common'volta e.

I c aim 1. In an apparatus of the character described, a source of highfrequency currents,

and means for influencing said high frequency currents, comprlsing awinding through whlch the hlgh frequency currents may flow, a secondWinding, an iron core for said wlndings, an ampllfymg thermionic valve,said second winding being connected 2. In an apparatus of the characterdescrlbed, a source of high frequency currents, and means forinfluencing said high frequency currents, comprising a winding throughwhich the high frequency currents may flow, a second winding, an ironcore for said windings, an amplifying thermionic valve, said secondwinding being connected in series with the closed circuit of the valve,

1 means for impressing signal representing valve, saidsecond windingbeing connected in series with the closed circuit of the valve, meansfor impressing signal representing currents upon the closed circuit ofthe valve, and an auxiliary winding upon the core, and a source ofdirect current for energizing said auxiliary winding.

4. In an apparatus of the character described, a source of highfrequency currents, and means for influencing said high frequencycurrents, comprising a winding through which the high frequency currentsmay flow, a second winding, an iron core for said windings, anamplifying thermionic valve, said second winding being connected inseries with the closed circuit of the valve, means. for impressingsignal representing currents upon the closed circuit of the val e,

an auxiliary Winding upon the core, a source of direct current forenergizing the auxiliary winding, and choke coils to prevent highfrequency current flowing through the any iliary winding.

In testimony whereof I have signed this specification in the presen e oftwo witnesses.

.LEO PUNGS.

lVitnesses OTTO SCHUEICH.

KATHE SECEK.

